using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Text;

namespace DPumpHydr.WinFrmUI.WenSkin.Json.Serialization
{
	/// <summary>
	/// Represents a trace writer that writes to memory. When the trace message limit is
	/// reached then old trace messages will be removed as new messages are added.
	/// </summary>
	public class MemoryTraceWriter : ITraceWriter
	{
		private readonly Queue<string> _traceMessages;

		/// <summary>
		/// Gets the <see cref="T:System.Diagnostics.TraceLevel" /> that will be used to filter the trace messages passed to the writer.
		/// For example a filter level of <code>Info</code> will exclude <code>Verbose</code> messages and include <code>Info</code>,
		/// <code>Warning</code> and <code>Error</code> messages.
		/// </summary>
		/// <value>
		/// The <see cref="T:System.Diagnostics.TraceLevel" /> that will be used to filter the trace messages passed to the writer.
		/// </value>
		public TraceLevel LevelFilter { get; set; }

		/// <summary>
		/// Initializes a new instance of the <see cref="T:Newtonsoft.Json.Serialization.MemoryTraceWriter" /> class.
		/// </summary>
		public MemoryTraceWriter()
		{
			LevelFilter = TraceLevel.Verbose;
			_traceMessages = new Queue<string>();
		}

		/// <summary>
		/// Writes the specified trace level, message and optional exception.
		/// </summary>
		/// <param name="level">The <see cref="T:System.Diagnostics.TraceLevel" /> at which to write this trace.</param>
		/// <param name="message">The trace message.</param>
		/// <param name="ex">The trace exception. This parameter is optional.</param>
		public void Trace(TraceLevel level, string message, Exception ex)
		{
			if (_traceMessages.Count >= 1000)
			{
				_traceMessages.Dequeue();
			}
			StringBuilder stringBuilder = new StringBuilder();
			stringBuilder.Append(DateTime.Now.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fff", CultureInfo.InvariantCulture));
			stringBuilder.Append(" ");
			stringBuilder.Append(level.ToString("g"));
			stringBuilder.Append(" ");
			stringBuilder.Append(message);
			_traceMessages.Enqueue(stringBuilder.ToString());
		}

		/// <summary>
		/// Returns an enumeration of the most recent trace messages.
		/// </summary>
		/// <returns>An enumeration of the most recent trace messages.</returns>
		public IEnumerable<string> GetTraceMessages()
		{
			return _traceMessages;
		}

		/// <summary>
		/// Returns a <see cref="T:System.String" /> of the most recent trace messages.
		/// </summary>
		/// <returns>
		/// A <see cref="T:System.String" /> of the most recent trace messages.
		/// </returns>
		public override string ToString()
		{
			StringBuilder stringBuilder = new StringBuilder();
			foreach (string traceMessage in _traceMessages)
			{
				if (stringBuilder.Length > 0)
				{
					stringBuilder.AppendLine();
				}
				stringBuilder.Append(traceMessage);
			}
			return stringBuilder.ToString();
		}
	}
}